A 40,000-year-old archaeological site in northern China has unearthed the earliest evidence of ochre processing in east Asia, researchers say. The site was discovered at Xiamabei in the Nihewan Basin, in the northern Chinese province of Hebei. Ochre pieces and tools found in the area suggest that the clay earth pigment was processed there, via grinding and pounding, to produce powders of different colours and grain sizes. Near lumps of ochre, archaeologists unearthed a hammer stone as well as a flat limestone slab that showed signs of battering. In a…